Fibroscan, Liver Elastography, and Non-Invasive Liver Assessments

• Estimating liver stiffness or tissue elasticity by measuring shear wave propagation speed (cs)
• Applying blood enzyme and protein levels into fibrosis scores

Liver Biopsy: Strengths and Limitations

Liver biopsy remains the imperfect but important gold standard for diagnosing liver disease and staging fibrosis. Its strength lies in its long-established history and the diversity of findings in one test. Without it, things are not always as they seem. It provides essential information where:

• The cause of liver abnormalities is unclear. For example, a patient with diabetes, obesity, and abnormal liver enzymes may have autoimmune hepatitis (AIH) or an overlap of AIH and steatohepatitis. A treated AIH patient with persistent enzyme elevation may have inadequately treated AIH or may have developed metabolic dysfunction-associated fatty liver disease (MAFLD) after steroid-induced weight gain.
• Unexpected findings such as granulomatous inflammation, bile duct injury, or venous congestion are possible.
• Measurement of tissue metal content (e.g., hemochromatosis, Wilson’s disease) is required.

However, biopsy is invasive and carries non-trivial risks, including:

• Pain, hypotension
• Haemorrhage
• Injury to adjacent organs (gallbladder, colon, pleura, kidney, pancreas)
• Sampling error: liver biopsies sample only about 1/50,000 of the total liver volume. Even high-quality percutaneous biopsies (~25 mm) misclassify fibrosis stage approximately 25% of the time compared to larger surgical specimens.

Liver Stiffness Measurement (LSM) with Elastography

The stiffness of your liver can be measured non-invasively with elastography. This is most commonly done at the time of a routine liver ultrasound using shear wave elastography (SWE). In specialist practice, transient elastography (TE) or magnetic resonance elastography (MRE) may be used.

Fibroscan® (Echosens, Paris) uses vibration-controlled transient elastography (VCTE). It was the first commercially available elastography method and remains the technique with the most advanced quality criteria, validation, and evidence base. It is a 10-minute, non-invasive, painless procedure experienced much like a liver ultrasound. A 5 MHz ultrasound transducer probe, mounted on the axis of a vibrator, transmits mild-amplitude, low-frequency vibrations (50 Hz) into the liver tissue, inducing an elastic shear wave that propagates through the underlying tissue. Patients describe the sensation as unusual but not painful — like a gentle flick or tap against the side. The velocity of the wave is directly related to tissue stiffness. The technique measures stiffness in a cylindrical volume approximately 1 cm in diameter and 4 cm in length, amounting to about 1/500 of the entire liver volume — 100 times larger than the volume sampled by a typical liver biopsy.

Shear Wave Elastography (SWE) is the most commonly used method in general radiology practices. SWE is performed as part of a standard ultrasound examination, using acoustic pulses from the ultrasound probe to generate internal shear waves within the liver. Like Fibroscan, SWE measures how fast these waves travel through the liver to estimate stiffness. Patients usually do not feel any sensation during SWE. Although the measurement method differs slightly, SWE provides a reliable and non-invasive way to assess liver health in routine clinical practice. Most radiology practices report liver stiffness using Shear Wave Elastography (SWE), often incorrectly using the brand "Fibroscan". SWE results can vary slightly between machines and software versions, due to differences in calibration and algorithms. Much like bone densitometry (DEXA), it is often impractical to ensure the same machine or software is used over years of follow-up. Fibroscan (TE) remains the most validated and standardised method for liver stiffness assessment. However, SWE shows comparable accuracy at the extremes — particularly when liver stiffness is <7.5 kPa or >9.0 kPa.

Magnetic Resonance Elastography (MRE) uses external vibrations, like TE, to generate mechanical waves through the liver. Specialised MRI sequences then image the propagation of these waves to create a detailed liver stiffness map. It is rarely ordered but MRE provides highly accurate assessment across the whole liver and is particularly useful when ultrasound-based elastography is limited, such as in large or multiple liver cysts/lesions, obesity or ascites.